126 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



The appearance of lagging or belated chromosomes has been 

 described for a great number of species and the phenomenon is 

 associated with \arying degrees of abnormality in the general 

 behavior of the cells in which it occurs. Whether in the case of 

 D. ohovata such bodies are really chromosomes is certainly a 

 question and my studies, to be described below, furnish some 

 interesting suggestions in this connection. 



Strasburger ('82) and later Juel ('97) have observed undoubted 

 chromosomes on the spindles after the completion of the reduc- 

 tion divisions of the pollen mother-cells in Hemerocallis fulva. 

 Strasburger and Juel both observed that these belated chromo- 

 somes become surrounded by nuclear membranes and form dwarf 

 nuclei and later dwarf pollen grains. Juel emphasizes the fact 

 that every chromatic mass can become an individual cell and 

 later divide. It must be remembered that already Wimmel ('50) 

 for Fuchsia, Hofmeister ('48, '61) for Passiflora caerulea and 

 Iris pumila, Tangl ('82) for Hemerocallis fulva, Wille ('86) for 

 twenty-three species of different flowering plants had found that 

 a number of pollen grains less and greater than four may arise 

 from a single pollen mother-cell by failure of the daughter pollen 

 mother-cells to divide or by subsequent division of the cells of 

 the tetrad. These views were later shared by Miss Lyon ('98) for 

 Euphorbia coroUata and Fullmer ('99) for Hemerocallis fidva. 

 Beer ('01) confirmed Juel's conclusions. He re-investigated 

 Wimmel's results on Fuchsia and found that some chromosomes 

 lag behind on the spindle after the first division and finally give 

 rise to dwarf nuclei. Less frequently these chromosomes fail to 

 become nuclei and then they rapidly disintegrate. 



Latour ('08) in his study of the development of pollen of 

 Agave attemiata noticed groups of chromosome-like bodies in the 

 cytoplasm and on the spindle in the first division of the pollen 

 mother-cell. These bodies look in all respects like chromosomes. 

 Each body soon becomes enveloped in a" nuclear membrane and 

 may then disintegrate, or several of them may unite to form a 

 larger nucleus or they may join the body of the main nucleus. 



Interesting abnormalities in division of the male germ cells 

 have likewise been observed in a number of hybrids. The anoma- 

 lies seem to be closely related to the appearance of chromosome- 

 like bodies. Juel ('00) investigated the cytology of the hybrid 



